Not Applicable.
The present invention relates to vehicle wheel alignment and more particularly, to an improved system for installing alignment adjustment components, such as cams, wedges, adjustable ball joints, and upper strut mounting plates which are used to adjust toe, caster, and camber alignment angles, and which usually require removal and reinstallation of a vehicle wheel rim and tire assembly.
As is well known in the automotive industry, some automotive vehicles utilize a cam bolt installed in a two-bolt strut to adjust the camber orientation of the automotive vehicle. The amount of adjustment and the orientation of this cam bolt primarily determines the amount of change in camber, but may also affect caster depending upon how the strut is mounted to the vehicle frame. A separate cam bolt is required for each vehicle wheel rim and tire assembly. It is also well known to use various wedges to adjust the camber of a particular wheel rim and tire assembly. Camber adjustment wedges come in various types, each having different sizes and configurations. Similarly, adjustable ball joints and upper strut mounting plates are used to offset camber and caster, and are available in a variety of sizes and configurations, each providing a varying degree of adjustment.
In order to utilize cam bolts, wedges, adjustable ball joints and upper strut mounting plates, an alignment technician is usually required to remove the vehicle wheel rim and tire assembly for installation of these parts. For cam bolts utilized to change a vehicle""s camber alignment angle only, the orientation of the cam bolt in the two-bolt strut regulates the amount of camber change. These cam bolts may be installed in such a position so as to result in a near zero error in camber, as compared to specifications. Most of these cam bolt installations require the alignment technician to remove the vehicle wheel rim and tire assembly in order to replace existing attachment bolts with the cam bolts. During this process, it is a common practice in the industry today to use a magnetic camber gauge, configured to measure only the camber alignment angle, attached to the vehicle brake disk to aid in the adjustment of the cam bolt close to the proper alignment angle.
Alternatively, the entire wheel alignment procedure may be performed with the vehicle wheel rim and tire assembly removed, using a system such as the Acculign 4000 Wheelless Alignment System(trademark), sold by Norkar Technologies, Inc. of Naperville, Ill. However, such xe2x80x9cwheel-lessxe2x80x9d alignment systems are impractical to use, as they require the prior removal of all vehicle wheels prior to performing a vehicle wheel alignment procedure, even if wheel removal is not required to perform an adjustment on one or more of the vehicle wheels.
Cam bolts may be supplied by the original equipment manufacturer (OEM), or by an after-market parts manufacturer such as Northstar Manufacturing Company, Inc. Many times, the alignment technician may not have a required OEM cam bolt from a particular part manufacturer in stock. In such situations, it would be desirable to select another cam bolt from stock which can provide the desired camber change. There are other part manufacturers that provide parts books where an appropriate substitute part can be looked up, however this all takes time and, in many cases, the technician will not go to the extra effort required to obtain a suitable substitute cam bolt to make the necessary adjustment.
To install a cam bolt, the standard industry procedure requires the following steps:
1. Measure the current camber, caster, and toe alignment angles using conventional wheel alignment sensors, such as angle transducers or optical targets;
2. Note the amount of camber change necessary to adjust the measured camber angle such that it conforms to the recommended or desired camber angle for the vehicle;
3. In most situations, jack up the front axle of the vehicle and remove the wheel alignment sensor and the wheel rim and tire assembly;
4. Install a magnetic camber gauge on the brake rotor and calibrate it to zero;
5. Remove one of the installed bolts of a two bolt strut and replace it with an adjustment cam bolt in the correct orientation as specified by the cam bolt installation instructions;
6. Loosen the remaining bolt of the two-bolt strut;
7. Adjust the installed cam bolt until the desired amount of camber change is shown on the magnetic camber gauge;
8. Tighten both bolts in the strut;
9. Reinstall the wheel rim and tire assembly;
10. Reattach the wheel alignment sensor;
11. Re-compensate the wheel alignment sensor to account for any change in runout caused by reattaching the wheel adapter to the wheel rim and tire assembly;
12. Lower the front axle back to the runway;
13. Re-measure the wheel alignment angles;
14. Verify that the change in alignment angles resulting from the installation of the cam bolt correspond to the desired change;
15. Repeat steps 3-14 if the resulting alignment angle change is not correct and if removal of the wheel rim and tire assembly is required, or readjust the installed part and repeat steps 13-15.
From the steps of the adjustment procedure outlined above, it is clear that the accuracy of the camber change attained during the installation of the cam bolt using the magnetic camber gauge does not equal the accuracy that is eventually attained using the alignment sensors mounted to the vehicle wheel rim and tire assembly to measure all of the alignment angles. This often results in the repeating of the time-consuming steps 3-14. This method can be improved upon, both in the accuracy of the final camber measurement, and in a reduction in overall vehicle wheel alignment time.
One such improved system, described in U.S. Pat. No. 6,064,927 to Molbach utilizes the operator-input characteristics of an already-installed alignment adjustment component when calculating the characteristics of a replacement alignment component to alter a wheel alignment angle.
Briefly, a wheel alignment adjustment system of the present invention includes sensing apparatus for sensing alignment characteristics of a vehicle to be aligned, and a memory for storing alignment specifications for a plurality of vehicles and alignment adjustment parts. A fixture is provided to secure the sensing apparatus to a wheel hub of the vehicle upon removal of the vehicle wheel rim and tire assembly, and a logic circuit is provided to determine from the sensed alignment characteristics of one or more alignment angles, and from the corresponding alignment angle specifications, an adjustment to after the vehicle alignment characteristics. A display is also included for displaying to a user a representation of the determined alignment.
The fixture of the present invention is configured for attachment to a vehicle wheel hub following removal of a vehicle wheel rim and tire assembly. The fixture provides a mounting to which a wheel alignment sensor or wheel alignment target may be secured, thereby permitting measurement of one or more of the vehicle wheel alignment angle parameters from the position and orientation of the vehicle wheel hub, in contrast to the camber-only measurements obtained from the use of prior art magnetic camber gauges.
A method of the present invention facilitates adjusting vehicle wheel alignment, and in adjusting vehicle wheel camber and caster. The method comprises the following steps:
1. Measure the current camber, caster, and toe alignment angles using conventional wheel alignment sensors, such as angle transducers or optical targets;
2. Note the amount of camber change necessary to adjust the measured camber angle such that it conforms to the recommended or desired camber angle for the vehicle;
3. In most situations, jack up the front axle of the vehicle and remove the wheel alignment sensor and the wheel rim and tire assembly;
4. Secure a wheel alignment sensor or wheel alignment target to the wheel hub; measure the wheel alignment of the wheel hub;
5. Calculate a change in alignment angles between the stored vehicle wheel rim and tire assembly measurement and the wheel hub measurement to provide current vehicle wheel alignment measurements;
6. Adjust or replace alignment components in response to the current vehicle wheel alignment measurements; removing the wheel alignment sensor or wheel alignment target from the wheel hub;
7. Reinstalling the vehicle wheel rim and tire assembly and the alignment sensor;
8. Re-compensate the wheel alignment sensor to account for any change in runout caused by reattaching the wheel adapter to the wheel rim and tire assembly; and
9. Lower the front axle back to the runway.
The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings.